On soine Comhinations ofPlaiina. 21J) 



of the metallic sulphurets in union with sulphuretted hy- 

 drogen. This novel field ot" inquiry has hitherto been neg- 

 lected ; but it cannot be unworthy the attention of chemists, 

 and it promises to lead to the explanation of many difficult 

 or obscure problems in chemistry. 



Since the publication of my paper *'0n the Combinations 

 of Sulphur and Phosphorus with Platina," I have ob- 

 served a slight inadvertency I had committed, in the use of' 

 the words super and suh. In conformity with the language 

 of chemistry, those compounds should have been called sul- 

 phuret and super-sulphuret ; and phosphoret and super- 

 phosphoret. In prefixing the words sziper and sub to the 

 common names, sulphuret, phosphoret, &c. in any in- 

 stance, it seems evidently to be implied that there are 

 three distinct combinations of the kind ; and in a relative 

 sense, one is said to contain a deficiency, the other an ex- 

 cess, and the third, an intermediate proportion of the in- 

 flammable principle. What however, was at first used by 

 accident and erroneously, must now be adopted from de- 

 sign, in the case of the compounds of platina with sulphur, 

 if ihc experiments detailed in the preceding pages are correct. 

 I have already stated that the substance obtained by 

 heating the hydrosulphuret of platina to redness in close 

 vessels, is analogous in its physical and chemical properties 

 to the super-sulphuret of platina. Thus its particles are 

 loosely coherent, it is tasteless, it gives lustre to the fingers 

 or paper like black-lead. It is unaffected by air and water, 

 is insoluble in the mineral acids, and is decompounded by 

 the agency of heat and air, with similar phasnomena to 

 the super-sulphuret. It differs however in some respects 

 from ihis substance. Thus its colour is blueish black, and 

 the proportion of sulphur it contains, does not exceed 22 

 per cent. 



In two experiments in which five grains of this substance 

 were decomposed at a red heat in a platina crucible, 3*9 

 grains of platina were obtained. 

 And 5 : 3'9 : : 100 : 78. 



In a third experiment, nine grains of it afforded rather 

 more than seven grains of platina. Hence it may be pre- 

 sumed that 100 grains of this substance contain 

 Platina 78 

 Sulphur 22 



100 

 From a comparison of my former experiments with 



these. 



